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More services...Help Needed: Comsol solving Error
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3 Replies
Last post: August 15, 2012 5:43am UTC
August 14, 2012 6:14pm UTC
Help Needed: Comsol solving Error
Hi
I am new to Comsol Multiphysics 4.2a. I built a model & try to run it but after clicking compute and it gave me an error
specifying
the following feature has encountered a problem:
-Feature: Stationary Solver 1 (sol1/s1)
-Error: Unknown Function.
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August 14, 2012 7:06pm UTC in response to Yogesh Suman
Re: Help Needed: Comsol solving Error
Hi,
Maybe you should check again your inputs (function expression, parameter, variables....),
And this link below hopes to help you: www.comsol.com/community/forums/general/thread/25832/
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August 15, 2012 1:04am UTC in response to Thanh Le
Re: Help Needed: Comsol solving Error
Hi , the Model I built is somehow running after checking the function and variable function. But my Variable expression has actually the rate expression where one of the concentration term (cD) is raised to 7.5(fraction) . How to write this term fraction in Comsol Multiphysics 4.2a. If I use the fraction term, the comsol is not able to evaluate the expression. if I am making it a whole number 8, then I am getting wrong result and concentration profile is not converging for any reactant & product.
here is my Rate expression which I am writing in variables.
rA=((-k)*(cA-(cC^3*cD^8/Kp/cB^4))/(1+(10^5*cC^3*cD^7.5/cB^4)+(cC*cD^2/cB))).
I am attaching the model build up file, made in Comsol 4.2a , please check if any other error is there which is giving problem.
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August 15, 2012 5:43am UTC in response to Yogesh Suman
Re: Help Needed: Comsol solving Error
Hi
are you getting an "unit" warning flag (equation in orange) or a typo error (equation in red) ?
because the units will get wring if you use such fractions of powers, but that is a warning, and COMSOL is calculating correctly.
I suspect it's in fact your equation that is not fully respecting the transfer of units, formally there is a unit conversion term missing
--
Good luck
Ivar
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